The invention relates to a method for determining the position of a tool of a rock drill in a known system of coordination relative to rock when using a rock drilling equipment comprising a base, at least one drilling boom mounted pivotally relative to the base and a rock drill connected pivotally relative to the boom to the other end of the boom and provided with a tool, in which method the position of the base of the rock drilling equipment in said system of coordination is determined and the position of the tool in said system of coordination is determined on the basis of the position of the base.
In excavating underground spaces, the accuracy of excavation is highly significant--the space to be excavated, e.g. a traffic tunnel, has been set a nominal measure which must not be reduced. When using the drilling/explosion method, drilling accuracy has a significant effect on the accuracy of excavation. In order to improve the drilling accuracy of holes, the positions of planned holes can be measured in advance with separate measuring devices and marked on the rock surface. Another method is to use instrumented or automatic drilling equipments in which the drilling boom is provided with sensors measuring the position of its joints; on the basis of the sensors the position and direction of the rock drill and thus of its tool relative to the base of the equipment can be determined--when this information is connected to a separately determined position and direction of the base of the equipment, the position and direction of the drill relative to the planned drill pattern can be determined and thus controlled. Regardless of the use of different methods, drilling accuracy has in practice been variable. This is because the methods require either handiwork or skill or that the measuring of the position of the joints of the drilling boom are sensitive to e.g. variation in the mechanical characteristics of the parts of the boom caused by wear and exterior forces acting on the boom. The variation in drilling accuracy leads, for example, to that in practice, more rock has to be excavated as a precaution than was planned. This causes additional costs in drilling, in explosion, in handling the blasted rock and in supporting the space. The variation in drilling accuracy is also harmful when excavating ores in which case the excavation of extra rock only incurs costs. Also, the precise direction and positioning of a tool is difficult in other rock drilling activity, such as when extracting off rock blocks with a percussion hammer by means of a striking tool or when doing any essential work with varying rock drilling equipments.
Finnish Patent Application 884,970 discloses an arrangement in which a feed beam of a rock drilling equipment is directed by using at least three laser beams the direction and position of which relative to the general system of coordination is known and by placing transmitters/receivers at each beam and at the feed beam at a distance from one another so that the direction and position of the feed beam in the general system of coordination of the tunnel can be measured on the basis of the oscilllation waves from the transmitters. This arrangement is suitable for long hole drilling but it is difficult to apply to tunnel drilling because laser beams have to be detached from their positions for the duration of explosion so that they would not be damaged. Further, if drilling equipments comprising more than one feed beam are used, not even three laser beams are necessarily enough so that the direction and position of all feed beams could be measured by means of them.
British Patent Application 2 180 117 discloses a method in which the position of the measuring tip is determined by using three measuring units mounted at fixed positions in the surroundings and two detectors mounted to the shaft of the measuring tip, whereby each measuring unit measures the position and distance of the detector and on the basis of this the position of the measuring tip is calculated. This arrangement requires that the measuring units are fixedly mounted in the surroundings, wherefore this method cannot be applied as such to rock drilling, nor can the arrangement disclosed in said Finnish Patent Application.
The object of this invention is to achieve such a method for measuring the position of a tool of a rock drill of a rock drilling equipment that can be used effectively and easily in all drilling and also when using more rock drilling equipments, if required.
The method of the invention is characterized in that the position of the tool relative to the base is determined by measuring, using at least three measuring devices situated at a known position relative to the base and at a distance from one another, wherein at least two are attached to the base, and at least one measuring device is located at a known position relative to the tool. At least some of the measuring devices comprise a transmitter for transmitting oscilllation energy and correspondingly, at least some of the measuring devices comprise a receiver for receiving oscilllation energy. The distance between the transmitters and receivers is measured on the basis of the oscilllation energy transmitted by each transmitter; the distances between the receivers and transmitters are calculated on the basis of the measured distances; and the position of the tool relative to the base is determined on the basis of the distances calculated.
The essential idea of the invention is that at least two measuring devices, that is, transmitters or receivers, mounted in the base of the rock drilling equipment are used and similarly, receivers or transmitters arranged at a known position relative to each rock drill or, when desired, in both cases transmitter-receivers, whereby the position of the rock drills and their tools can always be determined relative to the base. A further essential idea of the invention is that the position of the base of the rock drilling equipment relative to the rock in the general system of coordination is determined in some manner known per se, such as by means of laser or fixed point navigation, whereby when determining the position of the rock drill relative to the base, they are at the same time determined relative to the general system of coordination. According to one preferred embodiment of the invention, a separate transmitter-receiver unit, for example, can be used to help in determining the position of the rock drills. The transmitter-receiver unit is placed at a suitable position in the vicinity of the rock to be drilled, such as below rock drills or booms after which the position of this separate transmitter-receiver unit is determined by means of measuring devices fixedly mounted in the base after which the separate unit can be used for measuring the position of the rock drills.
A logical and readily useable measurement is achieved with the method according to the invention at the same time as a reliable measurement is obtained in all conditions by using several different measuring devices.